Switching power supplies or voltage regulators are popular for high power applications because of their high efficiency and the small amount of area/volume consumed by such regulators. Widely accepted switching voltage regulators include buck, boost, buck-boost, forward, flyback, half-bridge, full-bridge, and SEPIC topologies. Multiphase buck converters are particularly well suited for providing high current at low voltages needed by high-performance integrated circuits such as microprocessors, graphics processors, and network processors. Buck converters are typically implemented with active components such as a pulse width modulation (PWM) controller IC (integrated circuit), driver, power MOSFETs (metal-oxide-semiconductor field-effect transistors), and passive components such as inductors, transformers or coupled inductors, capacitors, and resistors. Parallel converters are also used in applications where high current requirements can be met by connecting multiple output converters in parallel and applying current sharing between them to meet the total output current requirement. The terms ‘multiphase regulator’ and ‘parallel converter’, and ‘output phase’ and ‘output converter’ are used interchangeably herein.
The large number of components in multiphase regulators and the typically high output current and power of such systems make it desirable to detect any component or connection failures in order to verify the full functionality of these systems and ensure that the voltage regulator operates properly over its entire operating range. Voltage, current, power and temperature monitoring are commonly implemented to ensure proper operation under varying, unpredictable and unforeseen operating conditions. These systems typically monitor voltage and current of the input and output terminals of the total system or of individual output phases.
There are many failure conditions in multiphase regulators where the regulator may still provide regulation under some conditions, but fail when the operating conditions change. For example, a voltage regulator with missing output phase components or connections may still properly regulate the output voltage under no load or light load conditions, but fail when the load current increases. The system may be able to regulate at the expected voltage, current, and temperature operating range under the no load or light load conditions, but fails to regulate when the load current increases. Additionally, the voltage regulator may operate in a suboptimal condition, at poor efficiency, for example, which often leads to thermal problems at high load currents. Most conventional systems provide simple fault protection based on voltage, current, power, and temperature monitoring, but fail to provide sophisticated fault protection that protects against more subtle or difficult to detect conditions where the regulator operates properly under some conditions, but not others.